Slide valves serving as discharge valves for metallurgical vessels are disclosed in the German publication 32 23 181 A1 and the German publication 40 12 093 C1. These slide valves include a plate which generally consists of ceramic and is shiftable in its own plane. The plate has a through opening which, by displacement of the plate, can be brought into register with the discharge opening of a vessel containing a melt. When the axis of the discharge opening is vertical, the plate lies, and is shiftable, in a horizontal plane.
The Swiss publication 374 454 teaches a rotary slide valve having a plurality of plates. The plate on the discharge side of the valve is rotatable and the valve is controlled, i.e., opened and closed, by rotating such plate.
The European patent application 0 234 877 A1 discloses a bottom pressure casting process in which a casting mold is filled via a bottom inlet having a horizontal axis. For solidification, the mold is rotated 180 degrees about this axis. The inlet remains open and no provision is made for closing the inlet. The vessel containing the melt for the mold is located below the inlet and, after the mold has been rotated, the pressure is reduced and the inlet empties into the vessel due to gravity.
Should the filling of a mold through a bottom inlet with subsequent rotation of the mold be applied to a gravity casting process where the vessel containing the melt is located above the inlet, a valve must be available to close off the mold from the vessel. If the hydrostatic pressure in the vessel is to be maintained in the mold during solidification, the valve must be able to keep the mold and the vessel in communication without a loss in sealing action.
Valves of the type described above are not suitable for discharge openings having horizontal axes. This is particularly true where a mold directly contacts a valve and the mold is rotated about a horizontal axis after filling of the mold.